Pluto's Heart May Hold an Icy Underground Ocean

Two new studies on Pluto were published on Wednesday, revealing a controversy about what lies beneath an icy impact basin in the center of the dwarf planet.

In the first study, planetary scientist James Keane reports that the western lobe of this heart - known as Sputnik Planitia - may have acted like an extra weight to tilt the planet off its original spin axis. The second study, led by planetary scientist Francis Nimmo, furthers these findings by suggesting that Sputnik Planitia may be so heavy because it is hiding a secret ocean beneath Pluto's icy crust.

"Sputnik Planitia is a hole in the ground. So normally you'd expect it to have less weight, not more weight," Nimmo explained.

The data from New Horizons supports Nimmo's theory; the planet has cracks on its surface which are characteristic marks of a planet expanding and contracting as parts of its ocean melt and freeze. And if there is water on Pluto, it makes sense that it would well up beneath Sputnik Planitia, where the planet's crust is thinner. This in turn would make this spot heavier than the rest of the planet, because liquid water is denser than ice.

But Keane and his colleagues do not necessarily agree with Nimmo's explaination. They note that Sputnik Planitia is full of volatile compounds such at nitrogen. Though these compounds would be gasses on the tepid surface of Earth, Pluto is so cold that these gasses freeze and behave like glaciers - and it's even colder at lower elevations, so nitrogen and methane probably get trapped in deep basins like Sputnik Planitia. But perhaps the most crucial component to this theory is the fact that solid nitrogen is denser than the frozen water that makes up the rest of the planet - meaning that the extra weight that caused the planetary tilt is accounted for.

And even if this ocean does exist, it doesn't necessarily mean we'll be finding Plutonic life anytime soon. The hypothesized ocean would be extremely cold and slushy with ice - not a prime candidate for extraterrestrial life. But as one of the researchers, Richard Binzel, stated, "one is careful to never say the word impossible."